Change in jet stream could mean longer, harsher winters

CHICAGO, Feb. 18 (UPI) -- The jet stream is taking a slower, more circuitous route across North America, the result being longer-lasting, more extreme weather patterns -- scientists say.

Presenting their findings at the annual meeting of the American Association for the Advancement of Science, held recently in Chicago, researchers Jennifer Francis and Mark Serreze said the change in jet stream behavior is likely due to rapidly warming temperatures in the Arctic.

“This does seem to suggest that weather patterns are changing and people are noticing that the weather in their area is not what it used to be,” Francis, a professor at Rutger University’s Institute of Marine and Coastal Sciences, told meeting attendees.

The jet stream, a typically fast-moving, fairly straight line of air, is driven by the temperature difference between the poles and the tropics. As that difference has lessened, researchers say, the jet stream is circulating with less gusto. And like a river that slows down, the jet stream is taking a longer, more serpentine path -- pushing cold weather farther south and warm weather farther north.

The slow speed of the jet stream also means new and unusual weather patterns are sticking around for longer periods of time, with storms dumping larger amounts of snow and rain.

Serreze, the director of the U.S. National Snow and Ice Data Center in Colorado, said the loss of ice sheets in the polar regions has helped accelerate rising Arctic temperatures.

“Fundamentally, the strong warming that might drive this is tied in with the loss of sea-ice cover that we’re seeing, because the sea-ice cover acts as this lid that separates the ocean from a colder atmosphere,” Serreze explained. “If we remove that lid, we pump all this heat up into the atmosphere.”